This invention relates to improved accessibility to communications network base stations mounted to a vertically movable platform within a tower interior.
Cellular telephone base stations typically have an electronics assembly mounted where it is readily accessible to a technician and one or more antennas mounted on an elevated structure to increase the line-of-sight range of the base station. Recently, a smaller cell site, called a microcell, has been developed to cover "hot spots" and "dead spots". The microcell uses less power and provides fewer channels than a "normal" cell site and was designed for a smaller coverage area. However, for some applications it would be advantageous to increase the coverage area of the microcell. Increased coverage area could be achieved by installing a more powerful radio frequency amplifier in the microcell. However, the size of the box containing the microcell is too small to accommodate the more powerful amplifier and to dissipate the additional heat generated thereby.
The increased coverage area could also be achieved by radiating from a taller tower, but if the cell site is at the base of the tower, significant losses occur in the cabling between the cell site and the antennas. In any event, the microcell antenna may be integrated with the electronics in the same box. Accordingly, it would be advantageous to locate the microcell at the top of the tower, since changing the elevation of the microcell from twenty feet to one hundred feet would increase the coverage area by a factor of about four. However, active electronics on the top of a tower need maintenance, so that the electronics either has to be lowered to a technician or the technician has to be raised to the electronics. It would be preferable to be able to raise and lower the electronics. This has been done in the past by using a cable and a winch with pulleys at the top of the tower and with a platform holding the electronics on the outside of the tower, along with the hoist mechanism. It has been proposed to contain the microcell platform within the confines of the tower interior for reasons of safety, structural integrity, esthetics, etc.
Since the microcells have a limited horizontal angular coverage range (on the order of 120.degree.), full coverage requires that at least three microcells be mounted to the platform. It would be desirable to mount all the microcells at the same level on the platform, rather than stacking them vertically. However, a typical tower is an open latticework structure of triangular cross section which limits the space available for mounting the microcells. While three microcells can be mounted in the available triangular space, it has been found that the door of each microcell is prevented from opening by interference with an adjacent microcell. It would therefore be desirable to have a mounting arrangement wherein the microcells are mounted to the platform all at the same level while still allowing each microcell door to be opened to allow maintenance of the microcell.